This invention relates to X-ray film exposure apparatus and, more particularly, to such apparatus wherein X-ray film in a cassette is exposed to a light density scale and, simultaneously, to predetermined indicia, and to a method of using such apparatus.
To facilitate the correlation of the indentity of a subject, such as a patient in a hospital, with a particular X-ray photograph, a film identification apparatus has been developed, such as that disclosed and claimed in U.S. Pat. No. 3,959,657, assigned to the assignee of the present invention. With this apparatus, an identification card is prepared, such as by typing, and inserted into the apparatus. Then, when an X-ray film cassette is loaded onto the apparatus, a luminescent element is energized to expose the X-ray film in the cassette to the patient identifying information on the card. Then (or prior to this light-exposure operation), the X-ray film cassette is exposed to an X-ray image of the patient. Upon development of the X-ray film, a viewable image of the X-ray photograph and the patient identifying information simultaneously is produced.
In general, exposure of the film to the patient identification information and the X-ray of the patient can be satisfactorily controlled such that substantially the same light and X-ray intensities are obtained for many exposure operations over an extended period of time. However, it is possible that, during the developing operation, various characteristics and variables of development may change. Also, film quality and its characteristics, as well as other factors, may vary over time. Thus, the quality or brightness of X-ray photographs taken days apart may vary. Hence, it is desirable to detect such variations so that suitable measures can be effected to correct such undesirable changes.
If a light-density scale formed of plural, for example, four, areas or strips of different densities, such as achromatic filter elements, is reproduced on the X-ray film for each X-ray photograph taken, then the quality of the developed images of selected X-ray photographs can be compared to each other. In the event of insufficient development, for example, the respective reproduced light-density scale of one X-ray photograph will appear generally lighter than the corresponding light-density scale of another photograph. Conversely, in the event of excessive development, the light-density scale of one X-ray photograph will appear darker than the corresponding light-density scale of another developed X-ray photograph.
Heretofore there have been various proposals for recording a light-density scale on X-ray film. The apparatus for carrying this out has exhibited a number of deficiencies, however, and for the most part necessitated a darkroom or other light-tight enclosure, thereby adding to the difficulty and inconvenience in its use.